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(No Model.)

C. H. EDSON.

L GUT-OFF VALVE. No. 276,528. Patented Apr. 24,1883.

- NESSES:

UNITED STATES PATENT OFFICE.

CHARLES H. EDSON, OF UANISTEO, NEW YORK.

CUT-OFF VALVE.

SPECIFICATION forming part of Letters Patent No. 276,528, dated April 24, 1883. Application filed September 6, 1882. (No model.)

To atl whom it may concern 7 Be it known that I, CHARLES H. EDSON,

of Oanisteo,in the county of Steuben and State of New York, have invented a new and Improved Out-Oii' Valve, of which the following is a full, clear, and exact description.

My invention consists in a main rotary valve for steam-engines, having within it a rotary cut-off valve whose ports are larger than those of the main valve.

Reference is to be had to the accompanying drawings, forming part of this specification,

in which similar letters of reference indicate corresponding parts in both the figures.

Figure l is a longitudinal section of my'improved valve and cut-0ft, showing the same as applied to an engine-cylinder, a portion of the cylinder being shown in cross-section. Fig. 2 is a transverse section on the line 3 y of Fig. 1.

A is the cylinder, formed with steam passages a a at each end, one end only being shown with its attached valve.

B is the valve-case, having a central cavity of tapering form, longitudinally by preference; butsaid cavity may be cylindrical.

(J is the revolving valve, contained within the case B, upon an axis, 11, that extends through equal parts.

the end of the case, where a suitable stuffingbox is provided. The axis of the valve is to be connected by suitable gearing to the main shaft of the engine, so that the valve will be revolved once for every two revolutions of the main shaft of the engine. The valve 0 is formed hollow, and with ports d d in its sides diametrically opposite.

D is the cut-0E valve, constructed in tapering form to fit the interior of the valve, and also hollow. The cutoff valve is formed with slots or openings 0 at its opposite sides, which are of a greater width than the openings of the main valve, and divide the cut-ofi' in two (The object of having the ports wider than the ports of the main valve is to prevent, upon the movement of the cut-off valve, the steam from being throttled at the beginning of the stroke, which would occur it the ports were of the same size, and also to cut off the steam at any part of the stroke of the engine.) It is attached upon the end of a stem, f, which extends through the end of the case B, and is to be connected with a governor of any suitable character operating to give to the cut-ofi', when the speed of the engine increases, a rotation in the direction opposite to the revolution of the valve. The cavity of the valve-case B is longer than the valve 0, so that a steam-space, g, is left in the end of the case, from which steam passes through the cut-off to the ports of the valve. Thereis also a space in the case at the smaller end of the valve 0, to allow endwise movement as the valve wears, thereby insuring the valve remaining steam-tight. A similar space is provided between the smaller end of the cut-off D and the end of the valve 0. With the tapering form of valve and cut-0ft the steam-pressure will act to press them to their seats and to take up any wear upon the seats. At the same time the pressure will not be sutficient to create excessive friction.

In operation, steam is admitted to the cylinder through the ports (I of the valve 0 at every half-revolution of the valve. crease of speed beyond the normal point, the cut-off, being connected with the governor, is given a slight rotation in the direction opposite to the movement of the main valve, thereby closing the port 01 and cutting off the steam at an earlier point in the stroke of the piston.

This will continue until the speed is sut'ticiently valve and cut-off. They might have but one opening, and the valve be revolved once to each revolution of the main shaft; butin that case the friction and wear would be materially increased.

I am aware of the patent to W. A. L. Kirk, August 28, 1866, No. 57,518, for cut-off valve, the same consisting of one hollow valve within the other, and having ports in their peripheries of equal area but this construction 1 do not claim, broadly.

What I do claim is-- 1. In a cut-oft valve, the outer valve having ports diametrically opposite each other, in combination with an inner valve having cor- In case of in- 7 responding ports of increased area of openarea of opening, substantially as and for the ings, substantially as and. for the purpose depurpose described. scribed. 1 1 T 2. In a cut-off valve, the combination of the OHARLEb EDSOL' casing having a single port, the outer valve having ports diametrically opposite, and the inner valve having corresponding ports of increased Witnesses:

C. D. TABoR, WM. J. SHELLEY. 

